Commutator trimming tool



Jan. 19, 1.943. BOWKER 2,308,671

COMMUTATOR TRIMMING' TOOL Filed April 27, 1940 s Sheets-Sheet 1 mmvroaE) VJ Bow 1 6a A T1 ORNEYS.

Jan. 19,, 1943. E. BOWKER 8, 1

- COMMUTATOR TRIMMING TOOL Filed April 27, 1940 s Sheets-Shet 2 ATTORNEYS.

Jan. 19, 1943. E BO KER 2,308,671

COMMUTATOR TRIMMING TOOL Filed April 27, 1940 3 Sheets-Sheet a ,4 0 H 4w IL INVENTOR. .E'ruzzk B0 W266 A TTORNEYS.

Patented Jan. 19, 1943 UNITED STATE COMMUTATORTRIMMING TOOL ErvinBowker, Fall River, Mass, assignor of one-' third to Douglas J.Richardson, Fall River, Mass; and one-third to Majar W. Wheelock,

Tiverton, R. 1.

Application April 27, 1940, Serial No. 332,096

Claims.

This invention relates to a tool for trimming or re-surfacing thecommutator of an armature for an electric motor or generator; and hasfor one of its objects to provide a simple and inexpensive tool whichmay be used for the re-surfacing of the segment of a commutator and mayalso be used for cutting back the insulation between such segments.

Another object of this invention is to provide a tool which may be screwfed forward but which, when the forward feed has been completed, may bereturned to starting position by a sliding action without the necessityof a reverse rotation comparable to the forward screw feeding of thedevice.

Another object of the invention is to provide a tool the use of whichupon a commutator will sufflce to perform the desired function in muchless time than comparable tools which I know of whereby the result onthe work may be materially speeded up.

Another object of the invention is to so mount the bit of the devicethat it may be accurately adjusted such as through a threadedarrangement of a micrometer type.

Another object of the invention is to provide an extremely simpleconstruction of bit holder with inherent resiliency which may be drawntogether on the bit and the same securely held.

Another object of the invention is to provide an arrangement whereby theadjustment of the bit will be in a straight line toward and from thecenter of rotation and at right angles to the center of rotation at allpoints in its movement so that the same cutting edge of the bit ispresented regardless of the point in the range of its movement.

Another object of the invention is to provide a simple chuck with anarrangement whereby a true centralizing mounting of the fixed part ofthe device upon the armature shaft may be had with an arrangement forthe accommodation of varying sizes of armature shafts.

With these and other objects in view, the invention consists of certainnovel features of construction, as will be more fully described, andparticularly pointed out in the appended claims.

In the accompanying drawings:

Fig. 1 is a top plan view, partly in section, illustrating .my tool infull lines with the-armature upon which the device is to operate indotted line;

Fig. 2 is an end view of my tool showing the armature shaft in sectionand taken on substantially line 2--2 of Fi 1 looking in the direction ofthe arrows;

Fig. 3 is an opposite end view of the device with the armature shaftremoved; I

Fig. 4 is a section on line 4-4 of Fig. 1;

Fig. 5 is a, perspective view of the bit holder looking at one sidethereof Fig. 6 is a perspective view of the bit holder looking at theother side thereof Fig. 'l is a perspective view of a carrier memberthrough which various adjustments of the device may be readily made;

Fig. 8 is a sectional view of the member of Fig. 7 shown mounted inposition and taken on line 8-8 of Fig. 1;

Fig. 9 is a sectional view of the cylindrical part of my device which isfixed to the armature shaft;

Fig. 10 is a section on substantially line Ill-40 of Fig. 9,illustrating the armature shaft and split sleeve thereabout mounted inposition in this barrel member;

Fig. 11 is a perspective view of the arm which is mounted upon themember shown in Fig. 7 which engages the thread shown in Fig. 9;

Fig. 12 is a side elevation of the device with the undercutting tool forremoving the insulation between the armature segment shown as mounted inposition;

Fig. 13 is a section on line l3--I3 of Fig. 12;

Fig. 14 is a central sectional view of a modified form of the device.

It frequently occurs in electric generators or motors that the brusheswhich contact the commutator of the armature wear the commutator to suchan extent that the commutator must be trimmed or re-cut in order that asmooth surface be provided. The tool to which this invention relates isa device which is mounted upon the armature shaft when such armature isheld in a vice and by turning one of the parts of the device suchretracing of the feeding stroke may be eliminated I have arranged fora'disengagement of the feed so that the parts may be returned totheiroriginal starting position by sliding. Further, it has been knownin armature cutting tools that the bit which performs the cut is somounted that it swings through an arc to and from the center about whichthe parts operate; and in order to improve upon this arrangement I haveprovided a mounting of the tool bit so that it moves in a plane at rightangles to the center about which it turns and in a straight line towardand from such center. the tool, is presented to the work regardless ofits point of adjustment.

After an armature commutator is turned down, it frequently occurs thatthe insulation between the segment is at the same level being turneddown by the cutting of the tool; and it is necessary to undercut or cutaway the insulation between the segments so that the brush which Thus,the same edge of.

the same opening from which the bit was taken,

and then by holding the part which previously rotated in the vice anddisengaging the thread feed and the binding of the adjustment member sothat the same may slide, I may slide the tool along the line parallel tothe axis and by manually turning the same cut the insulation between thesegments that the desired undercutting may be performed; and thefollowing is a more detailed description of the present embodiment ofthis invention, illustrating the preierred means by which theseadvantageous results may be accomplished:

With reference to the drawings. designates generally an armature havinga shaft [6. winding l1 and a commutator N3, the same being held betweenthe jaws i9 and 26 of a vice at the workbench or other suitablelocation.

My device consists of a cylindrical barrel designated 2| which is fixedto the armature shaft, and a rotor part, designated generally 22, whichmay rotate about the barrel part as a bearing to carry a bit and providea machine cut on the outer surface of the commutator.

The barrel part, designated generally 2i, is shown in section in Figs. 9and 10 and consists of cylindrical block having a central cylindricalbore 23. The bore 23 extends but partially axially through thecylindrical block, while at its other end there is a square opening 26centrally located. A slot 21 is cut across on a cord of the cylindricalcircle, as illustrated in Fig. 10, so as to intersect the opening 26 andis arranged substantially parallel to one of the diagonals of the squarecentral opening 26. A jaw 28 is pivoted in this slot 21 by pin 29 sothat if any cylindrical member, such as the armature shaft l6 and sleeve30 which extends about the same, is placed in this square opening 26, itwill engage the walls thereof as at 3|, 32, which are in a V-shapedrelation one to the other while the jaw 28 will engage the same as at 33and provide a threepoint contact with the cylindrical portion to bindthe sam centrally in the barrel member. A bolt 34 having a head 35engaging a shoulder 36 in the recess 31 threadingly engages the jaw 28as at 38 so as to draw the jaw into locking position.

Various sleeves 3lLare provided for accommodating armature shafts ofdiilerent diameters.

The rotor part of the device, designated generally 22, consists of acasting providing a cylindrical body 40 with a cylindrical bore 4| and atop or head projection 42 and a downwardly extending leg 43. This leg issplit as at 44.- An abutment screw 46 is threaded in one portion of theleg 43 and abuts the other portion of the leg and serves to hold theseportions of the leg 43 apart and prevent the inherent action tending tocontract the bore 4i onto the cylindrical part 2! from exerting toogreat a binding action, thereon. A binding screw 45 is provided fordrawing the split portions together. Should wear occur. however,adjustment is provided by means of these adjustments 45, 46 extendingthrough these portions of the leg 43.

A substantially s uare recess 41 is milled in the head 42 in which theadjustment member,

designated generally 48, is slidably positioned. This member is providedwith a V-shaped groove 48 to receive a V-shaped gib 58 located in therecess 41 and adjustable therein by means of the screws 5i extendingthrough the side walls of the head 42. The adjustment of this gib ismore or less a precision affair, and accordingly, these screws are setbelow the surface of the head 42 and are sealed in position by sealingwax or the like. A clamping screw 52 having a thumb handle 53 serves tomove the gib 66 inwardly to blind1 the member 48 in a fixed position inthe An arm designated generally 54 (see Figs. 1 and 11) is provided withan ear 55 which is rockably mounted by means of its bearing opening 56upon the stud 51 formed by reducing to cylindrical formation one end ofthe member 48. This car fits against the abutment 58 formed by thisreduction, while the pin 88 extends into the slot 6| in this manner tolimit the movement of the arm rockably about this stud. The arm has anarcuate portion 62 which reaches within the threaded bushing 24 so thatthreads 63 on it may mesh with the thread 25 on this bushing. The arm isheld in positions of adjustment in or out of engagement by a hand nut 64engaging thread 65 on the end of the stud 51. The spring washer 66serves to lock this nut in binding positions by acting through a washer81 between it and the car 55.

At the opposite end of the adjustment member 48 I have provided a bitcarrier 69 which fits within the recess 16 in the member 48. This bitcarrier is recessed as at 1| and slotted as at 1|, while there is alateral slot 12 in the opposite side of the carrier. A bit 14 fitswithin the recess 1! and is bound therein by the screw 15 having handle16. The shank of this screw extends through the hole 11 in one side ofthe carrier and is in threaded engagement as at 18 with the other sideof the carrier while extending through slot 86 in the member. The hub 18of this handle engages the outer surface of the member 48 and draws thecarrier into the recess 10 into binding position.

For vertical adjustment I provide a screw 8i having a flange 83 toextend into slot 12 in the bit carrier, the screw 8| being threaded intothe member 48 which is recessed asat 84 to receive the flange 83 forgreater range of adjustment of the bit carrier. By turning the handle85, the bit carrier may be adjusted .to its desired position with thescrew 15 partially set up to bind the bit in position; and after thecorrect height is acquired, a further binding of' the bit in its carriermay be had by reason of further turning of the handle 16. The slot 1ienables a proper binding of the bit 14 in position, while, whenreleased, the

inherent resiliency in the carrier opens to permit release of the bitfor removal of the same.

In order to rotate the part 22 about the part 2|, I have provided an armextending upwardly at any convenient angle from the part 22 sufficientto provide the desired leverage for turning. Upon the upper edge of thisarm a pin 96 is mounted and upon the pin there is a handle 81 which mayrotate with reference to the pin.

For undercutting I provide a U-shaped carrier 81 having a leg 88 of asize to fit within the recess 1! from which the bit 14 is removed, thesame being bound in position by the screw 15 and handle 16 in the samemanner that the bit was bound in position. This carrier has mounted inits leg 89 a rotary cutter 98 operated by a crank reference to the head.

8| and handle 92, while there is a handle as positioned on the member 81for moving the member 8 forward during an undercutting operation.

In some cases instead of the cylindrical barrel being internallythreaded, I may form the barrel as illustrated in Fig. 14, the samebeing shown at I and provided with external threads IOI. In this casethe rotor-member I02 is provided with an adjustable member I03; onthelower surface thereof threads are provided at I94. Movement of thismember is permitted toward and from the threads NH. The member I03 isnormally urged radially outwardly from the threads by a shoe I05 andleaf spring I06, the member being shown operative to and from threadedengagement by cams I01 engaging the ends of the studs I08 and I09 andoperated by handle H0 to force the member through the bronze plate H lto and from threaded engagement; the same tool adjustment of fit isprovided in this member as heretofore provided in the other modifiedarrangement.

In operation, the armature, designated generally I5, is removed from thegenerator or motor and placed in a vice as illustrated in Fig. 1. Thebarrel part 2| of the device is clamped upon the armature shaft [6 so asto remain in fixed relation thereto. The adjustment member 48 is ad-Justed so that bit ll will commence at the edge of the armaturecommutator for cutting the same and is properly adjusted as to height.Thereafter, the arm 54 is swung into engagement with the threads 25 andis clamped into position by the hand nut 64. Then by grasping the handle91 and turning the member 22, the member is rotated about the barrel andis fed forward by the screw 25 so that the tool will cut the commutatorto true-up the same.

This cutting action usually causes the mica or other insulation betweenthe sections of the commutator to be at the same surface as thecommutator section, and this insulation must be undercut. For thisundercutting I remove the armature from the vice and clamp the leg 43 ofthe device in the vice; then I remove the bit 14 and replace it with thecarriage 81, adjusting the same to cause the tool 90 to take the properdepth cut by reason of the handle 85. Nut 64 is loosened and the arm 54is thrown out of engagement with the thread, while the binding screw 53is loosened so as to permit movement of the member 48 with The member 22is held in fixed relation in a vice or other suitable support while themember 48 is fed forwardly by its handle 83, while at the same time thecutter 90 is rotated through the crank 9| and handle 92. After one cutis performed, while the leg 43 of the device is held in the vice, thearmature is turned until the next insulation is presented to the cutterand the operation then repeated.

In this manner each undercutting may be performed by utilization ofsubstantially the same device as performed the function of trimming thecommutator of the armature.

The foregoing description is directed solely towards the constructionillustrated, but I desire it to be understood that I reserve theprivilege of resorting to all the mechanical changes to which the deviceis susceptible.

I claim:

1. In an armature commutator device, two relatively rotative parts,means for binding one part on the armature shaft, comprising an openingin the part with two flat surfaces in a V-shaped relation forming thewall of the opening, said bound part having at one section an outersurface forming a part of a cylinder, a jaw at said section within thecompletion of the cylinder to force a shaft to be bound against saidfiat surfaces, a cutting tool carried by the other part, threadsprovided on one of said parts, and means on the other part forreleasably engaging said threads for axially moving said parts uponrelative rotation thereof.

2. In an armature commutator device, a cylindrical barrel part having anopening therein with two flat surfaces forming the wall of the openingand having a V-shaped relation one to the other, said barrel having atone section an outer surface forming a part of a cylinder, a jaw at saidsection within the completion of said cylindrical outer surface to forcea shaft to be bound against said flat surfaces and bind the barrel partthereon, a rotary part revolvably and slidably mounted on the outercylindrical surface of the barrel part, and disengageable threaded meanson said parts for relatively axially moving the parts when relativelyrotated with said means engaged.

3. In an armature commutator device, a cylindrical barrel part providedwith means to clamp an armature shaft therein, said barrel part beingprovidedv with a bore and internal threads, a rotary part revolvably andslidably mounted on the outer cylindrical surface of the barrel part andcarrying a tool, an arm located in said .bore and swingably mounted onthe rotary part to threadingly engage said internal threads to feed thetool when the parts are relatively rotated, means to clamp said arm ineither engaged or disengaged position with said threads, and a handlemounted on said rotary part to revolve the same about said barrel foractuating said tool.

4. In an armature commutator device, two

relatively rotative and slidable parts, means for' binding one part onthe armature shaft, a cutting tool carried by the other part, one of theparts being provided with a central threaded bore and an arm pivoted onthe other part on an axis located at a point spaced from the axis ofsaid bore and provided with threads engaging the threads of the borefor'relatively axially moving said parts upon relative rotation thereof,said arm being movable about said pivot to cause engagement ordisengagement of said threads.

5. In an armature commutator device, a cylindrical barrel part providedwith a V-shaped opening, a clamping jaw to clamp an armature shaft insaid opening to hold the. same firmly therein, said barrel part beingprovided with a bore and internal threads, a rotary part revolvably andslidably mounted on the outer cylindrical surface of the barrel part, amember axially slidably mounted in said rotary part, a tool holdercarried by said member at one end, threaded means to adjust said toolholder in a straight line toward and from the axial center of saidbarrel part, an arm swingably'mounted on the other end of said member toextend into said barrel and threadingly engage said internal threads,means to clamp said arm in either engaged or disengaged position withsaid threads, and a handle mounted on said rotary part to revolve thesame about said barrel for actuating said tool.

ERVIN BOWKER.

h CERTIFICATE OF conmzc'rxon.

Patent No. 2,508,671. January 19, 151 .5.

ERVIN BOWKER.-'

It is hereby certified that error appears in the above numbered patentrequiring correction as follows: In the grant, lines 5 and 111., and inthe heading to the printed specification, name of sssignee, for "Majarw. wheelock" read "Major w. wheelock", as shown by the recordOf.ass1gr1- ments in this office; and that the said Letters Patentshould be read with this correction therein that the same may conform tothe record for the case in the Patent office;

Signed and sealed this 9th day of March, A. D. 1915.

Henry Van A'rsdale, (Seal) Acting Commissioner of Patents.

